Peripheral pump

ABSTRACT

The invention is a peripheral pump ( 1 ) comprising a pump body ( 11 ) with drive shaft ( 41 ) and external magnet ( 4 ), a pump shaft ( 2 ) with an impeller ( 5 ) and an internal magnet ( 3 ) suited to be set in motion by said external magnet ( 4 ), and one volute ( 12 ) suited to house said impeller ( 5 ) comprising two half-volutes ( 121, 122 ) suited to be joined to each other and to directly support said pump shaft ( 2 ), and wherein on said pump body ( 11 ) there is at least one cover ( 13 ) suited to keep said half-volutes ( 121, 122 ) joined and closed.

This patent relates to peripheral pumps, single and multistage, and in particular concerns a new peripheral pump, single or multistage.

Peripheral centrifugal pumps are already known in the prior art comprising a pump casing to house the motor connected to a drive shaft, a sealed chamber or a volute with an inlet and outlet for the liquid to circulate, inside which at least one impeller coupled with a pump shaft rotates.

The transmission of motion to said pump shaft, and therefore to the impeller, is achieved through an internal magnet, coupled to said pump shaft, said internal impeller being driven by a magnet of the pump shaft, or by an external magnet.

In the known peripheral pumps, said volute or component of the hydraulic pump is formed by one half by the pump body and the other half by a cover attachable to said pump body, for example through a closing ring.

Said cover and said pump body therefore have the dual function of supporting the pump shaft and forming the hydraulic system of said pump, creating the volute.

Said impeller and said magnet must rotate integrally with said pump shaft to make the pump work.

Peripheral pumps also include bushings or ball bearings mounted on the pump shaft to allow its rotation with respect to said volute, namely with respect to said cover and said pump body forming said volute.

A disadvantage of the known peripheral pumps is that the maintenance of the hydraulic system of the pump, of the internal magnet and/or the pump shaft and/or the impeller and/or the ball bearings requires precise disassembly operations, as well as the replacement of one or more of said components.

The subject of this patent is a new peripheral pump, single or multistage.

The main aim of this invention is to allow quick replacement and maintenance operations of the hydraulic group or cartridge, consisting of the impeller and internal magnet fitted on a pump shaft, and two half-volutes forming the volute of the impeller housing.

Another aim of the present invention is to ensure the transmission of the torque, preventing any relative rotation of the impeller or the internal magnet with respect to the pump shaft.

Another aim of the present invention is to allow the axial sliding of the impeller and/or the internal magnet with respect to the pump shaft.

Another aim of the present invention is to contain manufacturing costs, while ensuring reliability of operation.

These and other aims, direct and complementary, are achieved by the new peripheral pump, single or multi-stage, comprising in reference to its main parts, a pump body equipped with a pump shaft and at least one external magnet fitted on said shaft, a pump shaft with at least one impeller fitted on it, at least one internal magnet suited to be set in motion by said external magnet and fitted on said pump shaft also, and a volute suited to house said impeller, and where said volute comprises two half-volutes suited to be joined to each other and to support said pump shaft.

Said internal magnet and said impeller are solidly constrained to said pump shaft by one or more locking means, and possible support bushings or bearings or jackets.

In particular, the coupling between the pump shaft and the impeller may be guaranteed by a shrink fit with adequate negative allowance, and/or through one or more tolerance rings or radial springs, and/or by tabs inserted between the pump shaft and impeller, which also allows a limited axial sliding between the stop rings.

The coupling between the pump shaft and the internal magnet is guaranteed by one or more tolerance rings or radial springs, and/or by tabs inserted between the pump shaft and the impeller and/or through one or more lock pins.

On said group or cartridge comprising said pump shaft, internal magnet, impeller, half-volutes with possible bushings, the pump cover is then installed which is suited to hold said two half-volutes together and closed, preferably by compressing them together with at least one elastic means like an axial spring, an O-ring preferably made with an elastomer and also having a static seal function between said cover and the pump body, or another means.

Therefore, said cover and said pump body, unlike in known peripheral pumps, have no hydraulic functions and do not provide any support to the pump shaft, said functions being carried out directly by said half-volutes.

Said group or cartridge can be installed in the pump body by sliding it in, using one or more anti-rotation pins or keys and the shrink fitting technique, thus exploiting the negative allowance to prevent the relative rotation of the fixed components of the group, that is, said half-volutes and/or mechanical locking components.

Said group or cartridge is therefore quickly and easily removable from the pump body after the prior removal of just the cover, to perform any maintenance, replacement or repair operation.

The components of this invention can be made of metal and/or non-metal materials, such as ceramics, plastics, etc.

The characteristics of the invention shall be better described making reference to the drawings, attached by way of a non-limiting example.

FIG. 1 shows a side view of a cross section of the new invention to show part of the pump shaft (2), the impeller (5) and the internal magnet (3).

FIG. 1 a shows a cross section of the group or cartridge comprising the pump shaft (2), the impeller (5) the half-volutes (121, 122), and the internal magnet (3).

FIGS. 2 to 7 show possible embodiments of the new invention.

The new peripheral pump (1), single or multistage, comprises a pump body (11) with a drive shaft (41), and a volute (12), formed by two half-volutes (121, 122) joined between them and suited to create a sealed chamber (123) and support said pump shaft (2).

Within said volute (12) there is at least one impeller (5) fastened to said pump shaft (2), and an internal magnet (3) fastened with tabs to said pump shaft (2).

An external magnet (4), fastened in turn with tabs to a shaft (41) connected to an electric motor is suited to rotate said internal magnet (3).

On the group or cartridge formed by said pump shaft (2), said magnet (3), said impeller (5) and said half-volutes (121, 122), shown in detail in FIG. 1 a, the cover (13) of the pump body (11) is then installed, suited to hold said two half-volutes (121, 122) together and closed.

Said cover (13) guarantees the sealed coupling between said half-volutes (121, 122) by means of at least one elastic element, such as an axial spring, an O-ring, or another means.

Said impeller (5) and said internal magnet (3) must rotate integrally with said pump shaft (2).

According to the configurations shown in FIGS. 2 and 3, said impeller (5) and said internal magnet (3) are bound to said pump shaft (2) by one or more tolerance rings (6), adequately sized, that compensate for the dimensional changes of the components (5, 3, 2) due to temperature changes, ensuring the correct transmission of torque.

At least one of said rings (6) is inserted between said impeller (5) and said pump shaft (2), and at least one additional ring (6) is inserted between the hub (31) of said inner magnet (3) and said pump shaft (2).

To prevent the axial slippage of said internal magnet (3) it is foreseen that at least one locking ring (7) is installed on said pump shaft (2).

According to the invention, said pump (1) may also comprise a pair of supporting jackets (21), interposed between said pump shaft (2) and said half volutes (121, 122), as shown in FIG. 2.

In the alternative embodiment shown in FIG. 3, each of said half-volutes (121, 122) comprises a cylindrical surface (124) surrounding said pump shaft (2) without the interposition of bushes.

According to the embodiment shown in FIGS. 4 a and 4 b, said impeller (5) and said internal magnet (3) are bound to said drive shaft by means of tabs (8), respectively inserted between said impeller (5) and said pump shaft (2) and between said hub (31) of the internal magnet (3) and said pump shaft (2), ensuring the transmission of torque.

Said tabs (8) transmit the rotary motion and do not prevent axial sliding, with a stroke of a few millimetres, of said impeller (5) and said internal magnet (3) with respect to said pump shaft (2).

To prevent axial slippage of said internal magnet (3), this embodiment also includes the use of at least one stop ring (7) fitted on said pump shaft (2).

In the embodiment of FIG. 4 a, the pump (1) comprises said supporting jackets (21), interposed between said pump shaft (2) and said half-volutes (121, 122), while in the embodiment of FIG. 4 b, each of said half-volutes (121, 122) comprise a cylindrical surface (124) surrounding said pump shaft (2).

According to the configurations shown in FIGS. 5 a and 5 b, said impeller (5) is solidly bound to said pump shaft (2) with a negative allowance, while said internal magnet (3) is constrained to said pump shaft (2) by at least one tab (8), which allows it to slide axially with respect to the pump shaft (2) for several millimetres.

In particular, said impeller (5) is bound to said pump shaft (2) using the shrink fitting technique, so as to achieve an adequate negative allowance, sufficient to prevent the rotation of the impeller (5) with respect to the pump shaft (2).

To prevent the axial slippage of said internal magnet (3), this embodiment also foresees the use of at least one stop ring (7) fitted on said pump shaft (2).

In the embodiment in FIG. 5 a, the pump (1) comprises said supporting jackets (21), interposed between said pump shaft (2) and said half-volutes (121, 122), while in the embodiment in FIG. 5 b said half-volutes (121, 122) each comprise a cylindrical surface (124) surrounding said pump shaft (2).

According to the configurations shown in FIGS. 6 a and 6 b, said impeller (5) is bound to said pump shaft (2) with a negative allowance, preferably using the shrink fitting technique, while said internal magnet (3) is bound by at least one locking pin (9).

In the embodiment in FIG. 6 a, the pump (1) comprises said supporting jackets (21), interposed between said pump shaft (2) and said half-volutes (121, 122), while in the embodiment in FIG. 6 b, said half-volutes (121, 122) each comprise a cylindrical surface (124) surrounding said pump shaft (2).

According to the configurations shown in FIGS. 7 a and 7 b, said impeller (5) is bound to said pump shaft (2) with at least one tolerance ring (6), while said internal magnet (3) is bound to said pump shaft (2) with at least one locking pin (9).

In the embodiment in FIG. 7 a, the pump (1) comprises said supporting jackets (21), interposed between said pump shaft (2) and said half-volutes (121, 122), while in the embodiment in FIG. 7 b, said half-volutes (121, 122) each comprise a cylindrical surface (124) surrounding said pump shaft (2).

Said supporting jackets (21) or sliding bearings, when present, can be detached, and therefore replaced, or incorporated in said half-volutes (121, 122).

The group or cartridge formed by said pump shaft (2), said impeller (5), said internal magnet (3) and said half-volutes (121, 122), with or without said supporting jackets (21) can be installed in the pump body (11) by sliding it in with at least one anti-rotation pin or key.

Said unit can therefore be removed from the pump (11) following the simple removal of just the cover (13).

Alternatively, the unit can be installed using the shrink fitting technique and/or by mechanical locking.

Therefore with reference to the preceeding description and the attached drawings the following claims are made. 

The invention claimed is:
 1. A peripheral pump, single or multi-stage, comprising: a pump body with drive shaft and at least one external magnet fitted on said drive shaft; a pump shaft with at least one impeller installed on said pump shaft; at least one internal magnet suited to be set in motion by said external magnet and fitted on said pump shaft; and a volute suited to house said impeller, wherein said volute comprises at least two half-volutes suited to be joined to each other and to directly support said pump shaft, and wherein on said pump body there is at least one cover suited to keep said half-volutes joined and closed.
 2. The peripheral pump according to claim 1, further comprising at least one of an elastic element, an axial spring, or a static ring between said cover and said pump body.
 3. The peripheral pump according claim 1, wherein a group or cartridge formed by said pump shaft, said internal magnet, said impeller, and said half-volutes is installed on said pump body in a sliding and removable manner using one or more anti-rotation pins or keys, through shrinking-on or mechanical locking, in order to prevent a mutual rotation of at least said half-volutes.
 4. The peripheral pump according to claim 1, further comprising one pair of supporting jackets interposed between said pump shaft and said half-volutes.
 5. The peripheral pump according to claim 1, wherein each one of said half-volutes supports said pump shaft directly resting on portions of a cylindrical surface of said half-volutes without interposition of bushings.
 6. The peripheral pump according to claim 1, further comprising one or more elastic rings to constrain said impeller to provide an integral member with said pump shaft, said one or more elastic rings being inserted between said impeller and said pump shaft in order to compensate for size variations due to temperature variations, at the same time guaranteeing a correct transmission of torque.
 7. The peripheral pump according claim 1, further comprising one or more tabs inserted between said impeller and said pump shaft in order to transmit torque while allowing axial sliding.
 8. The peripheral pump according to claim 1, wherein said impeller is rigidly constrained to said pump shaft with interference, through shrinking-on, such to obtain a suitable interference, sufficient to prevent any rotation of the impeller with respect to the pump shaft.
 9. The peripheral pump according to claim 1, further comprising one or more elastic rings constraining said internal magnet to make said internal magnet integral with said pump shaft, said one or more elastic rings being inserted between a hub of said internal magnet and said pump shaft.
 10. The peripheral pump according to claim 9, further comprising one or more tabs inserted between said hub of the internal magnet and said pump shaft, in order to transmit torque and allow axial sliding. 